The assembly of workpieces, such as machinery having rotating parts, frequently requires the precise fitting of antifriction rolling elements such as ball or roller bearings. Tolerances of the manufactured workpiece parts may cause variations in the axial dimensions of the workpiece which may exceed allowable variations for the fitting of bearings therein and therefore often some method of selective fitting or tailoring of a compensating component is required. One method commonly employed is to measure the assembly of components and provide a shim or spacer selected to precisely obtain the desired fit, which may be either a small amount of free end play or clearance or some prescribed value of a preloading force on the assembly.
An early example of an arrangement for preloading ball bearing arrangements in a workpiece is illustrated by U.S. Pat. No. 2,101,130 to Christman. The Christman arrangement provides a deformable or crushable separator element between ball bearing races so that in the assembly of the parts, this separator may compensate for inaccuracies of the workpiece parts. Christman employs a press to deform his spaceing element to a preferred load, whereupon the workpiece parts are crimped or otherwise permanently fastened in position. In other words, Christman relatively moves his workpiece parts until a certain preload force is achieved, whereupon the parts are permanently affixed to complete the workpiece assembly.
Improvements on the spacer or similar sealing elements, over known types such as employed in the Christman device are clearly described in my U.S. Pat. Nos. 3,561,793, 3,595,588, 3,751,048, 3,774,896, 3,794,311 and 3,900,232, as well as my two copending Applications, U.S. Ser. Nos. 447,571, now Pat. No. 4,067,585, and 838,306, now U.S. Pat. No. 4,125,929 filed Mar. 4, 1974 and Sept. 30, 1977, respectively, and U.S. Pat. Nos. 3,726,576 and 3,672,019. Briefly, my improved annular spacing elements are designed to experience elastic deformation with a relatively linear stress-strain relationship followed by plastic deformation under a relatively constant load or force, and when the originally applied deforming force is removed, they again exhibit a relatively linear stress-strain relationship, displaced by the amount of plastic deformation from their original stress-strain relationship. Thus, attempting to apply directly the Christman compensating technique to my spacer or load determining elements would result in either no plastic deformation of my elements, or a complete crushing of my elements. This is due to the fact that Christman increases the compressing force until a prescribed value is achieved, whereupon he fastens his workpiece portions together in that position and under that prescribed load. This approach worked for the Christman arrangement since the Christman spacer element was essentially an annular spring. Further, Christman preloads bearings to a prescribed pressure by allowing for variations in the relative position between two housing portions when those housing portions are affixed together. Such variations in the relative position of the housing portions are the exception rather than the rule in modern day equipment where typically two housing portions are bolted or welded together at their meeting faces, rather than one portion being press-fit into another portion to a variable depth. Thus, the Christman arrangement is unsuited to most bearing spacing or loading problems.